2.4.7 the effect of enzyme conc on the rate of reaction

Question 1

what does the enzyme conc./availability depend on in living cells

Answer 1

rate of synthesis of an enzyme & it’s rate of degradation
–> directly controlled by cell

Question 2

how does a cell control enzyme synthesis

Answer 2

depending on the cell’s needs, genes (for synthesising certain enzymes) can be switched on/off

Question 3

advantages of enzyme degradation

Answer 3

• elimination of abnormally shaped proteins –> may accumulate/ harm the cell
• regulation of cell metabolism by eliminating any superfluous enzymes

Question 4

superfluous

Answer 4

surplus to requirements

Question 5

what is equally important as control of enzyme synthesis - in order for cell to regulate it’s metabolism

Answer 5

control of enzyme degradation

Question 6

what happens when enzyme conc. increases

Answer 6

• more active sites available
• more successful collisions between enzyme/substrate
• more ESC can form per unit time = rate of reaction increases

Question 7

what is the limiting factor

Answer 7

enzyme conc.
- as it increases, so does the rate of reaction

Question 8

when is the reaction at its maximum rate (if the substrate conc. is fixed/limited)

Answer 8

all substrate molecules are occupying an active site or will have occupied & have been released as product molecules

Question 9

the reaction is at it’s max. rate for the fixed substrate conc. so….

Answer 9

• if enzyme conc. increased further, there will be no increase in rate of reaction as extra active sites are unoccupied
• enzyme conc. is no longer limiting factor (enzyme conc. increases, rate of reaction does not)
• substrate conc. = limiting factor (NOW)